From d5571c7a563a7cc8751d9f4d543188fc1ac323a5 Mon Sep 17 00:00:00 2001 From: Roy Marples Date: Fri, 2 May 2014 06:40:21 +0000 Subject: [PATCH] Document why we don't send both FQDN and hostname options. --- dhcp.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/dhcp.c b/dhcp.c index e9f73ecf..636acc5a 100644 --- a/dhcp.c +++ b/dhcp.c @@ -828,6 +828,15 @@ make_message(struct dhcp_message **message, ifo->options & DHCPCD_HOSTNAME_SHORT ? 1 : 0); else hostname = ifo->hostname; + + /* + * RFC4702 3.1 States that if we send the Client FQDN option + * then we MUST NOT also send the Host Name option. + * Technically we could, but that is not RFC conformant and + * also seems to break some DHCP server implemetations such as + * Windows. On the other hand, ISC dhcpd is just as non RFC + * conformant by not accepting a partially qualified FQDN. + */ if (ifo->fqdn != FQDN_DISABLE) { /* IETF DHC-FQDN option (81), RFC4702 */ *p++ = DHO_FQDN;